1. Field of the Invention
The present invention relates to a less expensive high-frequency high-voltage power supply for efficiently feeding a high-frequency high-voltage to a large-sized capacitive load such as an ozonizer, or an A.C. corona type ionizer, an electric dust collector.
2. Description of the Known Art
Heretofore, in order to feed a high-frequency high-voltage to a large-sized capacitive load, the method has been employed in which a high-frequency primary power supply having a low voltage and a high power is constructed by making use of transistors, thyristors, thyratrons, transmitter tubes, etc. The output of the primary power supply is fed to a primary side (low voltage side) of a high-frequency high-voltage transformer, and the output on the secondary side (high voltage side) of the transformer is fed to an object load. However, in this case, since an ineffective power [K bar] to be fed to a load is remarkably large as compared to a power consumption [KW] of the load, the capacity [KVA] to be possessed by the above-mentioned high-frequency primary power supply and high-frequency high voltage transformer becomes excessively large, and hence the cost of the power supply becomes remarkably expensive. In addition, there was a shortcoming that the loss of the power supply was also large, and so, the efficiency was lowered. As a method for dealing with this problem, the method has been employed, in which an inductance having a value of L=1/.omega..sup.2 C.sub.L [H] (where .omega.=angular frequency of the power supply) that is adapted to compensate for a capacitance C.sub.L [F] of the above-mentioned capacitive load, is connected in parallel to the load to make the equivalent power-factor of the load equal to unity. However even in this case, since not only the number of turns of the secondary winding of the high-frequency high-voltage transformer is large but also sufficient inter-layer insulation as well as sufficient insulation of the secondary winding from the primary winding are necessitated, a leakage inductance l.sub.W and an inter-winding electrostatic capacitance C.sub.W of the secondary side become large. These hardly calculatable factors l.sub.W and C.sub.W would greatly influence the compensating conditions for the load capacitance, and so, it becomes very difficult to determine the value of the compensating inductance. Moreover, the parallel high resistance component R representing the power consumption of the above-referred capacitive load C.sub.L generally has remarkable nonlinearity because it is an equivalent resistance of the ozonizer discharge, corona discharge or the like. Therefore, the load circuit becomes a nonlinear type, and hence, not only compensation for the capacitance C.sub.L in a strict mean becomes impossible, but also even if an inductance L, which can approximately compensate for the capacitance C.sub.L at a certain operating point with regard to the current, voltage and frequency, is inserted, the compensation for the capacitance C.sub.L would become ineffective in response to slight change of the operating point. In other words, it is the present status of the art that the compensation for the load capacitance by means of the parallel inductance is also difficult. Hence sufficient reduction of the required capacity [KVA] of the high-frequency primary power supply and the high-frequency high-voltage transformer cannot be achieved either. Thus solution for the problems of high cost and large loss is difficult.